Delayed pharmacological effects of proctolin and CCAP on heartbeat in pupae of the tobacco hornworm, Manduca sexta

Abstract. The effects in vivo of cardioactive peptides proctolin, CCAP and leucomyosuppressin (LMS) are investigated by means of noninvasive optocardiographic or thermographic techniques in postdiapause pupae of Manduca sexta. A constant pattern of heartbeat reversal in these pupae is manifested by regular alternations of the forward orientated (anterograde) and the backward orientated (retrograde) cardiac pulsations, with a periodicity of some 5–10 min. The heartbeat pattern is monitored continuously for several hours before and 24 h after injection of the investigated peptides. Injections of Ringer solution alone cause a slight, almost immediate increase of the rate of the pupal heartbeat (0–10%), which lasts only for 20–30 min. Injection of proctolin, CCAP or LMS does not show any immediate cardiostimulating effects (beyond those of Ringer) at concentrations up to 2 × 10⁻⁶ M (calculated from µg of the injected peptide and 70% pupal water content; 5–7 g pupal body mass). By contrast, injections of proctolin and CCAP in the range of 10^-9 − 10^-6 M concentrations cause delayed effects on the heartbeat, which are manifested only several hours after the injections. The delayed effects involve prolonged, or even continuous periods of unidirectional, more efficient and faster anterograde pulsations. Consequently, the flow of haemolymph through the head and thoracic parts of the pupal body increases. In the case of proctolin, the prolonged anterograde cardiac activity usually starts 5 h after the injections and the effect persists for 7–12 h. Using CCAP, the stimulation of anterograde activity starts 2.5–3 h after injections and lasts usually 7–8 h. Very small doses of peptides (10^-8 − 10^-9 M) do not change the latency period significantly, but they decrease the duration of the response. The frequency of the systolic contractions of the heart does not increase during the prolonged anterograde phase. Injections of LMS to produce a final concentration of 10⁻⁶ M in the pupa induce pathophysiological disturbances of heartbeat reversal and peristalsis. The effects start with a delay of some 1.5–2.5 h after the injections. By contrast to the effects of proctolin and CCAP, LMS does not produce delayed anterograde cardiac pulsations. These results show that the most intensively investigated cardiostimulating peptides in vitro, proctolin and CCAP, have no direct cardiostimulating activity under physiological conditions in vivo. It is concluded therefore that the delayed pharmacological effects of these peptides observed in the pupae of M. sexta, represent a secondary effect, resulting from stimulation of nonspecific, extracardiac myotropic or other physiological functions.     

Trends in solventless sample preparation techniques for environmental analysis

The paper presents recent trends in solventless sample preparation techniques for environmental analysis. First, a general classification of solventless methods is given. Next, three of them, treated as preferable techniques, i.e. SPME, SDME and HS, are presented in detail, with respect to their usability and effectiveness for environmental samples. Examples of all discussed techniques are given in the tables.     

Analysis of the composition of bacterial communities in oil reservoirs from a southern offshore Brazilian basin

The aim of this study was to characterize and compare the bacterial community structure of two distinct oil samples from a petroleum field in Brazil by using both molecular, based on the construction of 16S rRNA gene libraries, and cultivation methods. Statistical comparisons of libraries based on Amplified Ribosomal DNA Restriction Analysis (ARDRA) data revealed no significant differences between the communities recovered in the non-biodegraded (NBD) and highly biodegraded oils (HBD). BlastN analysis of the 16S rRNA gene sequences representative of distinct ribotypes from both oils showed the presence of nine different bacterial genera in these samples, encompassing members of the genera Arcobacter, Halanaerobium, Marinobacter, Propionibacterium, Streptomyces, Leuconostoc, Acinetobacter, Bacillus and Streptococcus. Enrichments obtained using oil as inoculum and sole carbon source yielded bacterial isolates showing high 16S rRNA gene sequence similarity with Achromobacter xylosoxidans, Bacillus subtilis, Brevibacillus sp., Dietzia sp. and Methylobacterium sp. Comparison between the data obtained using cultivation-independent and enrichment cultures suggests that different selection of community members may occur when using distinct approaches. All the organisms found, except for Leuconostoc sp. and Streptococus sp., have been previously reported in the literature as hydrocarbon degraders and/or associated to oil field environments.     

细胞凋亡检测方法探讨

采用图例法和比较法分析评价细胞凋亡检测方法的应用范围和检测结果的相关性,指出只有选择多种适当的方法进行综合检测,才能对结果做出正确而合理的分析判断。流式细胞术简便、快速,从膜上分子、胞内蛋白到DNA水平全方位多角度分析凋亡,可作为检测细胞凋亡的首选方法。     

丹参生物工程的研究与开发

中药材的品质改良是中药现代化进程中的一个重要问题,现代生物工程技术是进行中药材品质改良的可行途径之一。对丹参的组织培养、毛状根诱导培养及基因工程等方面的最新进展作一综述,以期为利用生物工程技术遗传改良丹参品质提供一些参考。     

Factors Affecting Engorgement Behavior in the Salt Marsh Horse Fly, <Emphasis Type="Italic">Tabanus nigrovittatus</Emphasis> Macquart (Diptera: Tabanidae)

Female Tabanus nigrovittatus were field collected and used in laboratory experimentation to explore physiological and behavioral factors that affect engorgement. Previous studies showed sulfakinins act as feeding satiety factors in insects. This study demonstrates that sulfakinins have differing effects on engorgement that is dependent on the feeding technique used in the laboratory. The satiety effect of sulfakinin on flies engorging using the blood-soaked Kimwipe® feeding technique is not in agreement with previous experiments using an alternate feeding technique with artificial membranes. This study is the first to demonstrate that the temperature of blood is a significant factor for engorgement in this species. Also, the percentage of flies engorging is significantly different depending on the feeding technique used.     

Conifer Cover Increase in the Greater Yellowstone Ecosystem: Frequency,Rates, and Spatial Variation

Extensive fires in recent decades in the Greater Yellowstone Ecosystem (GYE) garnered much attention for causing a significant decrease in the extent of conifer forest cover. Meanwhile, conifer forests in unburned parts of the GYE have continued to increase in extent and density. Conifer cover increase has been well documented by repeat historical photography, but the average rate of increase and the spatial variation remain unquantified. We examined changes in conifer cover across biophysical gradients in the GYE based on stratified random samples from aerial photographs. The percent conifer cover for samples in 1971 and 1999 was quantified to determine the frequency and rate of conifer cover change. A slight majority of samples (56%) showed no change, whereas increases (22%) were balanced by decreases (22%). However, among samples that were not recently burned or logged, or already closed-canopy, nearly 40% increased in conifer cover, at an average annual rate of 0.22%. We quantified significant variability in the frequency and rate of conifer cover increase across gradients of elevation, aspect, vegetation type, and proximity to nearby conifer forest. The most dynamic locations were low density conifer woodlands on northerly aspects at lower elevations, with average annual rates of increase up to 0.51%. This study is significant because it demonstrates that rates of conifer cover increase vary across biophysical gradients, an important consideration for management of dynamic forest ecosystems. Improved understanding of this variability helps us to better understand what factors ultimately cause conifer cover increase. It is also a critical step towards accurate quantification of the magnitude of carbon uptake by conifer cover increase.     

Molecular cytology of the respiratory tract and pleura

There is growing evidence that molecular testing is feasible on all types of cytological preparation, which is fortunate as more diagnostic markers and biomarkers for targeted therapies are discovered for use in pulmonary and pleural malignancies. In this article we will discuss the pre-analytic, analytic, and post-analytic (interpretive) considerations for successful implementation of molecular tests for diagnostic and predictive markers in respiratory and pleural cytology. The vast majority of laboratories are familiar with, and have validated their molecular protocols for, formalin-fixed paraffin-embedded surgical specimens, which are not directly applicable to cytology specimens. Thus, rigorous validation must be performed for each type of fixative and cytology preparation before it is implemented in the clinical setting.     

Freezing behaviour facilitates bioelectric crypsis in cuttlefish faced with predation risk

Cephalopods, and in particular the cuttlefish Sepia officinalis, are common models for studies of camouflage and predator avoidance behaviour. Preventing detection by predators is especially important to this group of animals, most of which are soft-bodied, lack physical defences, and are subject to both visually and non-visually mediated detection. Here, we report a novel cryptic mechanism in S. officinalis in which bioelectric cues are reduced via a behavioural freeze response to a predator stimulus. The reduction of bioelectric fields created by the freeze-simulating stimulus resulted in a possible decrease in shark predation risk by reducing detectability. The freeze response may also facilitate other non-visual cryptic mechanisms to lower predation risk from a wide range of predator types.